Urine Formation Tubular Reabsorption & Secretion (PART II)

Question 1

Actions of ALDOSTERONE on LATE distal, cortical and medullary collecting tubules

• Increases ___ reabsorption - principal cells
• Increases ____ secretion - principal cells
• Increases___ secretion - intercalated cells

Answer 1

Na+

K+

H+

Question 2

ABNORMAL Aldosterone Production

_______ _________ (Primary aldosteronism Conn’s syndrome) - Na+ RETENTION, hypokalemia, alkalosis, hypertension.

________ _____________- Addison’s disease
Na+ WASTING, hyperkalemia, hypotension

Answer 2

Excess aldosterone

Aldosterone deficiency

Question 3

Control of Aldosterone Secretion

1. Factors that __________ aldosterone secretion
   • Angiotensin II
   • Increased K+
   • adrenocorticotrophic hormone (ACTH) (permissive role)
2. Factors that __________aldosterone secretion
   • Atrial natriuretic factor (ANF)
   • Increased Na+ concentration (osmolality)

Answer 3

increase

decrease

Question 4

Angiotensin II— INCREASES Na+ and Water Reabsorption

1. Stimulates ____________ secretion
2. Directly ___________ Na+ reabsorption (proximal, loop, distal, collecting tubules)
3. ___________ efferent arterioles
   - decreases peritubular capillary hydrostatic pressure
   - increases filtration fraction, which increases peritubular colloid osmotic pressure)

Answer 4

aldosterone

increases

Constricts

Question 5

Angiotensin II _______ renal tubular sodium reabsorption

Answer 5

increases

Question 6

Ang II constriction of efferent arterioles causes Na+ and

water retention and ________ excretion of waste products.

Answer 6

maintains

Question 7

Angiotensin II BLOCKADE decreases Na+ reabsorption and blood pressure

1. ACE inhibitors (captopril, benazipril, ramipril)
2. Ang II antagonists (losartan, candesartin, irbesartan)
3. Renin inhibitors (aliskirin)
   a. ______ aldosterone
   b. directly inhibit Na+ reabsorption
   c. decrease_________ arteriolar resistance

Answer 7

decrease

efferent

Question 8

Natriuresis and Diuresis = a _________ in Blood Pressure

Answer 8

DECREASE

Question 9

Antidiuretic Hormone (ADH)

• _________ H2O permeability and reabsorption in
distal and collecting tubules
• Allows differential control of H2O and solute ______
• Important controller of extracellular fluid osmolarity
• Secreted by __________ pituitary

Answer 9

Increases

excretion

posterior

Question 10

.ADH synthesis in the magnocellular neurons of hypothalamus, released by the posterior pituitary, and create action on the ________

Answer 10

kidneys

Question 11

Abnormalities of ADH x 2

1. Inappropriate ADH syndrome (excess ADH)
   - _____________ plasma osmolarity, hyponatremia
2. “____________” Diabetes insipidus (insufficient ADH)
   - increased plasma osmolarity, hypernatremia, excess thirst

Answer 11

decreased

Central

Question 12

Atrial natriuretic peptide increases Na+ EXCRETION

• Secreted by cardiac atria in response to stretch (increased blood volume)
• Directly _________ Na+ reabsorption
• Inhibits ______ release and aldosterone formation
• Increases ____
• Helps to minimize blood volume expansion

Answer 12

inhibits

renin

GFR

Question 13

Parathyroid hormone INCREASES renal Ca++reabsorption

Released by parathyroids in response to
DECREASED extracellular Ca++

• Increases Ca++ reabsorption by ________
• Increases Ca++ reabsorption by _______
• Decreases _____________ reabsorption
• Helps to increase extracellular Ca++

Answer 13

kidneys

gut

phosphate

Question 14

Sympathetic nervous system increases Na+ reabsorption

• Directly stimulates Na+ reabsorption
• Stimulates _______ release
• Decreases ___and _____ blood flow
(only at high levels of sympathetic stimulation)

Answer 14

renin

GFR

renal

Question 15

Increased Arterial Pressure DECREASES Na+ Reabsorption (Pressure Natriuresis)

• Increased peritubular capillary hydrostatic pressure
• Decreased _____ and __________
• Increased release of intrarenal natriuretic factors
- prostaglandins
- EDRF

Answer 15

renin

aldosterone

Question 16

Osmotic Effects on Reabsorption

1. Water is reabsorbed only by _________
2. Increasing the amount of unreabsorbed solutes in the tubules _____________ water reabsorption
   i.e., diabetes mellitus: unreabsorbed _________ in
   tubules causes diuresis and water loss
   i.e., osmotic diuretics (mannitol)

Answer 16

osmosis

decreases

glucose

Question 17

ABNORMAL Tubular Function: INCREASED Reabsorption

• _________ Syndrome: primary aldosterone EXCESS
• Glucocorticoid Remediable Aldosteronism (GRA) EXCESS aldosterone secretion due to abnormal control of aldosterone synthase by ACTH (GENETIC)
• ________ secreting tumor: excess Ang II formation
• Inappropriate ADH syndrome: EXCESS ADH
• __________ Syndrome: excess activity of amiloride sensitive Na+ channel (genetic)

Answer 17

Conn’s

Renin

Liddle’s

***Liddle’s Syndrome: Excess Activity of Amiloride
Sensitive Na+Channel in Late Distal and Cortical Collecting Tubules.

Question 18

Abnormal Tubular Function: DECREASED Reabsorption X 6

1. _______ Insipidus: DECREASED water reabsorption, hypernatremia
   - nephrogenic
   - lack of ADH
2. ________disease: DECREASED Na+ reabsorption and DECREASED K+ secretion; lack of aldosterone
3. _________ Syndrome: DECREASED Na+, Ca++, HCO3
   - reabsorption, hypotension; DECREASED activity of Na-K-2 Cl TRANSPORTER in THICK loop of Henle
4. _________ Syndrome: DECREASED NaCl reabsorption, hypotension; DECREASED activity of NaCl co-transporter in distal tubule (genetic)

Answer 18

Diabetes

Addison’s

Bartter’s

***Bartter’s Syndrome: Decreased Activity of Na-K-2Cl
Co-Transporter in THICK Ascending Loop of Henle

Gitleman’s

Question 19

Abnormal Tubular Function: DECREASED Reabsorption X 6

5. ______ syndrome: generalized decrease in reabsorption often in proximal tubules; causes: genetic, HEAVY METAL damage, DRUGS (tetracyclines), multiple myeloma, tubular necrosis (ischemia)
6. _____tubular acidosis: DECREASED H+ secretion,
   Increased HCO3
   - excretion, acidosis causes: genetic, renal injury, etc.

Answer 19

Fanconi

Renal

Question 20

Bartter’s Syndrome: DECREASED Activity of Na-K-2Cl
Co-Transporter in THICK Ascending Loop of Henle

Treatment: high NaCl, K+intakes, ______ blockers (e.g. aspirin)

Answer 20

prostaglandin

Question 21

Gitleman’s Syndrome: DECREASED NaCl Reabsorption in ______ Distal Tubule

Treatment: high NaCl and K+ intakes, Mg++ supplements

Answer 21

Early

Question 22

_________ secretion – the movement of substances out of the blood and into the tubular fluid; the reverse of
reabsorption.

Descending limb of the loop of Henle secretes _____
through diffusion

_________and collecting tubules secrete potssium,
hydrogen, and ammonium ions

Answer 22

Tubular

urea

Distal

Question 23

Tubular Secretion X 6

Important for:

1. Disposing of substances not already in the filtrate,
   such as certain _________
2. Eliminating undesirable substances or end products
   that have been _________ by passive processes
   (urea and uric acid)
3. Ridding the body of excess _____
4. Controlling blood pH
5. _________ – hormone that targets the cells of the
   distal and collecting tubule cells causing increased
   activity of the Na-K pumps
6. _________of hydrogen ions increases with increased blood hydrogen ion concentration

Answer 23

drugs

reabsorbed

K+

Aldosterone

Secretion

Question 24

Urine Composition X 7

• Approximately______ water
• ______ _________ – result of protein metabolism;
e.g., urea, uric acid, ammonia, and creatinine
•___________ – Na, K, NH4, Cl, HCO3, PO4, and SO4
• Toxins
• Pigments – urochromes
• Hormones – high hormone levels may spill into the
filtrate
• Abnormal constituents – such as blood, glucose,
albumin, casts, or calculi

Answer 24

95%

Nitrogenous wastes

Electrolytes